Add signature field support

base/shared/annotation.js

@@ -372,10 +372,10 @@ var WidgetAnnotation = (function WidgetAnnotationClosure() {
   var parent = Annotation.prototype;
   Util.inherit(WidgetAnnotation, Annotation, {
     isViewable: function WidgetAnnotation_isViewable() {
-      if (this.data.fieldType === 'Sig') {
-        TODO('unimplemented annotation type: Widget signature');
-        return false;
-      }
+//      if (this.data.fieldType === 'Sig') {
+//        TODO('unimplemented annotation type: Widget signature');
+//        return false;
+//      }
 
       return parent.isViewable.call(this);
     }

lib/pdfanno.js

@@ -148,6 +148,25 @@ function processFieldAttribute(jsFuncName, item) {
     }
 }
 
+function setupSignature(annotation, item) {
+    //PDF Spec p.695: field value is signature dict if signed
+    let sig = annotation.get('V');
+    if (!sig) return;
+
+    //PDF Spec p.728: get signature information
+    item.Sig = {};
+    let name = sig.get('Name');
+    if (name) item.Sig.Name = name;
+    let time = sig.get('M');
+    if (time) item.Sig.M = time;
+    let location = sig.get('Location');
+    if (location) item.Sig.Location = location;
+    let reason = sig.get('Reason');
+    if (reason) item.Sig.Reason = reason;
+    let contactInfo = sig.get('ContactInfo');
+    if (contactInfo) item.Sig.ContactInfo = contactInfo;
+}
+
 //END - MQZ 9/19/2012. Helper functions to parse acroForm elements
 
 class PDFAnno {
@@ -169,6 +188,9 @@ class PDFAnno {
         else if (item.fieldType == 'Tx') {
             setupFieldAttributes(annotation, item);
         }
+        else if (item.fieldType === 'Sig') {
+            setupSignature(annotation, item);
+        }
         else {
             nodeUtil.p2jwarn("Unknown fieldType: ", item);
         }

lib/pdffield.js

@@ -26,6 +26,7 @@ class PDFField {
                 retVal = true;
                 break;
             case 'Ch': retVal = true; break; //drop down
+            case 'Sig': retVal = true; break; //signature
             default:
                 nodeUtil.p2jwarn("Unsupported: field.fieldType of " + field.fieldType);
                 break;
@@ -222,6 +223,27 @@ class PDFField {
         this.Fields.push(anData);
     };
 
+    #addSignature(field) {
+        const anData = Object.assign({
+            style: 48,
+            T: {
+                Name: "signature",
+                TypeInfo: {}
+            }
+        }, this.#getFieldBaseData(field));
+
+        if (field.Sig) {
+            anData.Sig = {};
+            if (field.Sig.Name) anData.Sig.Name = field.Sig.Name;
+            if (field.Sig.M) anData.Sig.M = PDFUnit.dateToIso8601(field.Sig.M);
+            if (field.Sig.Location) anData.Sig.Location = field.Sig.Location;
+            if (field.Sig.Reason) anData.Sig.Reason = field.Sig.Reason;
+            if (field.Sig.ContactInfo) anData.Sig.ContactInfo = field.Sig.ContactInfo;
+        }
+
+        this.Fields.push(anData);
+    }
+
     // public instance methods
     processField() {
         this.field.TI = PDFField.tabIndex++;
@@ -232,6 +254,7 @@ class PDFField {
             case 'Rd': this.#addRadioButton(this.field);break;
             case 'Btn':this.#addLinkButton(this.field); break;
             case 'Ch': this.#addSelect(this.field); break;
+            case 'Sig': this.#addSignature(this.field); break;
         }
 
         this.clean();

lib/pdfunit.js

@@ -51,6 +51,29 @@ class PDFUnit {
         //MQZ. 07/29/2013: if color is not in dictionary, just return -1. The caller (pdffont, pdffill) will set the actual color
         return kColors.indexOf(color);
     }
+
+    static dateToIso8601(date) {
+        // PDF spec p.160
+        if (date.slice(0, 2) === 'D:') { // D: prefix is optional
+            date = date.slice(2);
+        }
+        let tz = 'Z';
+        let idx = date.search(/[Z+-]/); // timezone is optional
+        if (idx >= 0) {
+            tz = date.slice(idx);
+            if (tz !== 'Z') { // timezone format OHH'mm'
+                tz = tz.slice(0, 3) + ':' + tz.slice(4, 6);
+            }
+            date = date.slice(0, idx);
+        }
+        let yr = date.slice(0, 4); // everything after year is optional
+        let mth = date.slice(4, 6) || '01';
+        let day = date.slice(6, 8) || '01';
+        let hr = date.slice(8, 10) || '00';
+        let min = date.slice(10, 12) || '00';
+        let sec = date.slice(12, 14) || '00';
+        return yr + '-' + mth + '-' + day + 'T' + hr + ':' + min + ':' + sec + tz;
+    }
 }
 
 module.exports = PDFUnit;

readme.md

@@ -566,6 +566,37 @@ Another supported field attributes is "required": when form author mark a field
                     h: 0.85
                 }
 
+v2.X.X added support for the signature form element (Name: 'signature'). If the field has been signed, the 'Sig' property will be present, and will contain any of the following signature details if available:
+- 'Name' - Signer's name
+- 'M' - Time of signing in [ISO 8601](https://en.wikipedia.org/wiki/ISO_8601) format
+- 'Location' - Location of signing
+- 'Reason' - Reason for signing
+- 'ContactInfo' - Signer's contact information
+
+Signature example:
+
+                {
+                    style: 48,
+                    T: {
+                        Name: "signature",
+                        TypeInfo: {}
+                    },
+                    id: {
+                        Id: "SignatureFormField_1",
+                        EN: 0
+                    },
+                    TI: 0,
+                    AM: 16,
+                    x: 5.506,
+                    y: 31.394,
+                    w: 14.367,
+                    h: 4.241,
+                    Sig: {
+                        Name: "Signer Name",
+                        M: "2022-03-15T19:17:34-04:00"
+                    }
+                }
+
 ## Text Input Field Formatter Types
 
 v0.1.8 added text input field formatter types detection for